1. Field of Invention
This invention generally relates to passive direction locating antenna systems for radio waves, and is particularly concerned with circular antenna array systems that continuously observe over a complete 360.degree. arc in space to determine the spatial direction of an incoming wave and produce a digital output code representing the direction.
2. Description of the Prior Art
In the prior art, the spatial direction of an incoming radio wave has been often determined by the use of scanning antenna systems wherein a focused antenna beam is rotated or electrically scanned to sequentially observe each spatial direction and determine the angle or sector where the incoming wave is received. Both mechanical scanning systems using rotating antenna elements and electronic scanning systems using a rotating beam but stationary antenna elements have been used for this purpose.
It is also known in the prior art to use nonscanning linear antenna arrays that locate the spatial direction of an incoming wave by interferometric techniques. However such linear arrays observe over only a limited angular sector, and a series of such scanning arrays are required to observe over a wide arc such as over a complete 360.degree. arc in space for each axis.